criteria expressions

[Guest]

I have a table and form where there is a field named Supplier Source Code
where users enter the next available letter or double letters (A through GG
currently) and date that a supplier is approved. I need a button in the form
that will show the last letter used which probably should be based on the
latest date. I've made a query using the Source Code field and the date
issued field. Do I use one field in the query and use one expression or two
fields and two expressions? What is the expression I should use?

 

[John Spencer]

SQL Query would look like the following.

SELECT [SourceCode]
FROM YourTable
WHERE [DateIssued] =
(SELECT Max(DateIssued0
FROM YourTable)

If the last source code is based on the value of source code, then what are
the rules for generating source codes?
Is the sequence
A, AA, AB, AC...,B, BA, BB,..,G,GA, GB,...GG
Or is it
A, B, C, D, ...,Z, AA, AB, AC,..,AZ, BA, BB, BC,...,GA, GB, GC,...,GF, GG
Or is it something different?